I mean, the only way we know the placement of it in the timeline, it's because they said so, but, as far as I think, the game could be placed almost anywhere else.I wouldn't be surprised if they decided to change it's placement

... right. it didn't really matter when it takes place, so they made it happen between prime and echoze so that they could call it a prime game. that way more people would buy it. they're not going to just randomly "change" the timeline of the games.